CHICAGO (AFP) - Hundreds of rogue black holes may be roaming around the Milky Way waiting to engulf stars and planets that cross their path, US astronomers said Wednesday.

The astronomers believe these "intermediate mass" black holes are invisible except in rare circumstances and have been spawned by mergers of black holes within globular clusters -- swarms of stars held together by their mutual gravity.

These black holes are unlikely to pose a threat to Earth, but may engulf nebulae, stars and planets that stray into their paths, the researchers said.

"These rogue black holes are extremely unlikely to do any damage to us in the lifetime of the universe," said Kelly Holley-Bockelmann, an assistant professor of physics and astronomy at Vanderbilt University in Nashville, Tennessee.